The invention relates to an improved form of sucralose and a process for making it.
Sucralose (4,1xe2x80x2,6xe2x80x2-trichloro-4,1xe2x80x2,6xe2x80x2-trideoxy-galactosucrose) a high intensity sweetener made from sucrose, can be used in many food and beverage applications. Sucralose, unlike many artificial sweeteners, can be used in cooking and baking with no loss of sweetening power.
Sucralose is generally made following the procedures set forth in U.S. Pat. Nos. 4,362,869; 4,380,476; 4,801,700; 4,950,746; 5,470,969 and 5,498,709. In all these procedures one of the final steps in the synthesis is a deacylation followed by the crystallization of the sucralose. Laboratory scale methods for crystallizing sucralose have been described in U.S. Pat. Nos. 4,343,934; 5,141,860; 4,977,254; 4,783,526; 4,380,476; 5,298,611; 4,362,869; 4,801,700; and 4,980,463. As is described in many of these patents the deacylation of the sucralose precursor is performed in methanol with a catalytic amount of sodium methoxide. After completion of deacylation the resulting sucralose solution is contacted with an ion exchange resin to convert the residual sodium methoxide to methanol. The ion exchange resin is then removed and the volatile solvents and reaction byproducts are removed by co-distillation with water, which results in a solvent switch to water. The mixture is decolorized by contacting with activated carbon. The carbon is removed to provide a decolorized sucralose solution suitable for crystallizing sucralose. The sucralose solution is concentrated to about 55 weight percent sucralose (at about 50xc2x0 C.). The crystallization is performed by reducing the temperature to about 22xc2x0 C. and adding of about 2 percent sucralose seed crystals. The crystals that formed are separated from the mother liquor by centrifugation then dried. The mother liquor that is separated from the crystals is added to the next batch just prior to decolorization.
Unfortunately, this process has a few drawbacks.The mother liquor can become acidic over time. Additionally, the accumulation of impurities can interfere with the crystallization of sucralose, resulting in the need to periodically purge or discard the mother liquor. Crystalline sucralose, prepared as described above, generates minute amounts of hydrochloric acid, which reduces the shelf life of sucralose.
It is an object of the present invention to provide an improved process for producing a more stable form of crystalline sucralose.
It is another object of the present invention to provide an improved crystalline sucralose composition that exhibits increased stability.
We have discovered that addition of a buffer to the sucralose solution before crystallization significantly increases the stability of the sucralose crystallized from it and also increases the stability of the mother liquors during processing.
We have also discovered that by keeping the pH of the sucralose containing crystallization solution in the range of from about pH 5.5 to about pH 8.5 during the crystallization of sucralose the final stability of crystalline sucralose can be improved.
In another embodiment of the present invention, we have provided a stable crystalline sucralose product that does not develop an acetic acid odor upon storage.
In yet another embodiment of the present invention we have provided a process for the production of a stable crystalline sucralose product that does not develop an acetic acid odor upon storage.
In a further embodiment of the present invention we have also surprisingly discovered that crystalline sucralose with residual moisture content of from about 0.5 to about 10 percent by weight has improved stability.
In yet a further embodiment of the present invention we have discovered a product comprising crystalline sucralose in a container that will maintain the moisture content. Preferably the container will have moisture vapor transfer rate (MVTR) of not more than 0.25 gram water/100 square inches of surface area/24 hours, when tested at 38xc2x0 C. at 92 percent relative humidity.
These inventions and other inventions will be apparent to those skilled in the art from reading the following specification (including the Examples and Claims).